Just as a disclaimer, I am an iOS beginner, in a pretty unique position. I'm an intern learning on the job, with a hard deadline for a test app, with specific specs. So I unfortunately don't have the luxury of learning all that I should about xCode and objective C.
Anyways, I am trying to create a navigation menu similar to the iPad's slide out menu. I've looked at plenty of sample code given in response to questions like this in the past. It all works perfectly fine, but I can't understand all of what they're doing. I think this results from being fairly bewildered by view controllers and delegates. And, since I'm supposed to be writing this all by myself, I can't just build off of their existing code.
My plan for this working is to have one main view controller, containing the navigation menu in a table view. This is hidden behind a normal UIView, until a button is pressed, at which point the normal UIView slides offscreen enough to reveal the menu. Upon selection of a menu item, the normal UIView would slide back to its original position, and be replaced by the relevant UIView, controlled by its view controller. In other words, clicking on the menu item relating to "Home" would load the homeViewController.xib, controlled by the homeViewController. This would be loaded in that normal UIView subview, on top of the tableView.
I'm able to load a view in that normal UIView as a result of a button press.
homeViewController *_homeViewController = [[homeViewController alloc]initWithNibName:#"homeViewController"];
[self frontView] = _homeViewController.view;
There may be some syntax errors in that code, since its from memory. I'm not able to access the computer with my code on it at the moment, but that's the general gist. Basically, that places the home view nib on the frontView (that normal UIView that's over the table view), but its not connected to homeViewController. Or at least I think that's the issue, when I press a button, that's correctly connected between the nib and the homeViewController.h, and only set to NSLog in the .m file, the application crashes.
Any idea how to connect this nib to its viewController when displayed in this way? Or, to create the nib in IB, without the associated .h and .m files, and use the main view controller as the homeViewController as well? Or, if my logic is inherently flawed, what SHOULD I do? Something with NavigationControllers?
EDIT:
I also tried a new approach- changing homeViewController's file owner to viewController, and connecting the button on homeViewController's action to viewController. This too caused a crash upon pressing the button. I really think the issue is with having multiple view controllers acting on screen at once, or having multiple views from separate nibs, controlled by one view controller on screen at once.
I suspect that your immediate problem is that _homeViewController is being freed as soon as you leave whatever method that code is in. To fix this, create a strong property in this class that holds the _homeViewController for as long as its view is needed and allocate it to that property rather than a local variable. That way, buttons (or whatever) that are part of that view still have a valid controller object backing them.
In the long run, pushing or presenting view controllers when you need the screen to change is a much better strategy but, as I said, the immediate problem.... :)
Related
I made an app for my wife to track inventory. it has a couple of view controllers to enter a new item, display all items, search items, and display selected item. After switching through each view a couple of times (no particular order) all of the textfields become disabled (you cannot select them to change the value) across ALL of the view controllers. The buttons still work however. I have it setup so that when the user enters info into a particular cell, it saves it into memory so that if they switch views and then come back, the cells will get the data in the viewdidload method. Please Help!
*edit - I am using storyboard with a bunch of segues (i'm new to programming and self taught, so idk if this is the right way or not)... here is a pic of my storyboard
http://i.imgur.com/aT3PR0i.png
Ok, with a look at your storyboard, I think I see your problem. If your storyboard looks like somebody spilled spaghetti on it, it's not designed correctly. Specifically, it looks like you're going "backwards" (to controllers you've already been to) using segues -- that's not good. SEGUES ALWAYS INSTANTIATE NEW CONTROLLERS! So, if you go around in a circle a few times, you're adding more and more controllers to your project. To go backwards using segues, you need to use an unwind segue -- it's the only one that is an exception to the rule that segues always instantiate new controllers. The other ways to go backwards, without segues, are popping with navigation controllers, and dismissing modal controllers.
I can't really diagnose your immediate problem without a lot more information, but redesigning the storyboard using unwind segues would probably fix your problem.
Lets say I have a scene which includes a UIView container on the top half of the screen, and a UIView container on the bottom half of the screen and a few buttons at the very bottom of the screen.
Basically the bottom container will always display static text while the buttons across the bottom will change the content of the top container which may include an image, more buttons, or more text depending on what button is pressed on the bottom. Also each time a bottom button is pressed the top container is transitioned to the new view with a flip from bottom transition.
I have achieved this purely programmatically, but decided to convert my app to a storyboard file since it makes producing the rest of my app much faster and simpler, plus makes the code not look like a crazy mess.
My limited understanding of storyboards seems to deduce that I would need a separate story board scene for every UIView change, and Apple's coding conventions with storyboards seem to imply that we should use a new ViewController every time you create a new scene. All this adds up to an even bigger mess than I currently have.
Is there a better way of doing this? Am I misunderstanding something? If I am not confused, is there some way to make all these scene and view controller duplication cleaner?
The storyboard editor makes it difficult to do what you're describing, because it doesn't let you edit freestanding views associated with a scene.
I suggest you just create a separate nib (not storyboard) for each of the top-half views. These can exist separate from your storyboard. Your view controller (which is instantiated from the storyboard) can then load whichever nib it needs when a button is pressed, and put the view from the nib into its (the view controller's) top-level view.
There must be a way!
I accidentally opened one one day (see attached image). Although I have no idea how I did it and really really want to know, I cannot reproduce it, nor close it. The UIView opened when I was dragging my connection for the table header view from the Connections Inspector to the list of controls on the left side of the screen (not to the actual UIViewController).
I too am reworking a project with storyboards and have a similar problem with multiple views per UIViewController.
In this case it is a table header. I have other UIViewControllers in the project with the same configuration but I cannot get them to pop up either.
I'm creating an iPad app based on a UINavigationController (with the bar hidden) so I can push and pop other viewControllers for navigation around the app. However, I am now wanting to add a section in which there are two viewControllers that I want to be able to switch between, so in other words they are side-by-side, rather than hierarchical.
Is it okay to use a UITabBarController for this? I am aware that on the iPhone it is recommended they are used only at the root level of the app, but since this is an iPad app I wondered if I could use it? Also, I guess I need to create an empty viewController, create a UITabBarController within it and set the delegate to it, then add the two viewControllers to it... So in effect I will have a viewController within another viewController, and when I have done that in the past the results have been very flaky.
Can I do it this way? The only other way I can think of doing it is to have two plan UIViews within a UIViewController, but that also means I shouldn't really put any business logic in them (bad MVC!), and not being able to will be a right pain in the a**.
Any ideas?
Thanks!
:-Joe
EDIT: I also need to be able to swipe-animate between the two VCs within the TabBarController, AND have a menubar over the top which doesn't animate... Can I do this?
Sure.
I do this kind of thing all over the place in an app I'm working on. I actually have several different types of "toolbars" that can be optionally shown at different times.
What I do is create a "parent" member in my toolbar's class - and when a button is pressed, I have the toolbar call a method in the parent class to do whatever needs to be done - (i.e. display another view).
This avoids the whole mess of creating a view inside another view (or viewcontroller inside another viewcontroller - or whatever) - the toolbar can take the button hits, but all the views are opened by the root view/controller.
Hope this helps/makes sense!
Specifically, I have something like a game, with a menu screen made out of standard components. I want a button to switch to another view controller that the user will interact with for a while, then return to the menu screen. It seems like having the menu controller present the 'game' mode as a modal view controller is the most straightforward solution, but is this the best way to essentially replace the entire view? Is the whole menu (which may later become a deep nav or split controller) kept in memory as long as the modal controller is in front, and is this something I should bother to worry about?
There are really two parts to this question:
Which method of transitioning from one view to the next in an iPad application provides the best experience to the user?
Which method of transitioning from one view to the next is easiest to implement and best handles memory management?
I'm not going to try to address the first part of this question other than to point you to Apple's 'iPad Human Interface Guidelines' which says (among other things):
Reduce Full-Screen Transitions
Closely associate visual transitions with the content that’s changing. Instead of swapping in a whole new screen when some embedded information changes, try to update only the areas of the user interface that need it. As a general rule, prefer transitioning individual views and objects, not the screen. In most cases, flipping the entire screen is not recommended.
When you perform fewer full-screen transitions, your application has greater visual stability, which helps people keep track of where they are in their task. You can use UI elements such as split view and popover to lessen the need for full-screen transitions.
http://developer.apple.com/library/ios/prerelease/#documentation/General/Conceptual/iPadHIG/DesignGuidelines/DesignGuidelines.html
However, in your case I'd have thought a full-screen transition is entirely appropriate (but then I'm not a user experience expert).
In answer to the second part, yes displaying a new view controller modally seems like a good approach to take.
By default both the objects used by the menu view and those used by the modal view will be kept in memory - but the great thing about using UIViewController sub-classes is that they've got some default memory management built-in. If your application receives a memory warning whilst the modal view is being presented in full-screen mode, the menu view controller's views will be removed and it's 'viewDidUnload' method will be called. So in your implementation of this method you should release any objects you don't need and then recreate them as needed in the menu view controller's viewDidLoad method (which will be called again before the menu view is shown).
This is explained in more detail in the UIViewController class reference:
When a low-memory warning occurs, the UIViewController class purges its views if it knows it can reload or recreate them again later. If this happens, it also calls the viewDidUnload method to give your code a chance to relinquish ownership of any objects that are associated with your view hierarchy, including objects loaded with the nib file, objects created in your viewDidLoad method, and objects created lazily at runtime and added to the view hierarchy. Typically, if your view controller contains outlets (properties or raw variables that contain the IBOutlet keyword), you should use the viewDidUnload method to relinquish ownership of those outlets or any other view-related data that you no longer need.
http://developer.apple.com/library/ios/#documentation/uikit/reference/UIViewController_Class/Reference/Reference.html
I'm using Objective-C and Cocoa, whilst developing for Mac OS X - so not the iPhone/Cocoa Touch. (That said, I'd be interested if it was the same procedure for the iPhone)
I'm working on a preferences window for a simple app. I have a NSWindow with a toolbar - there are 5 different items on the toolbar, all of which need to bring up a different set of options.
So I set the NSToolbar and its items in Interface Builder, and then placed a custom view underneath the menu - taking up the rest of the window. My plan is to work out the interface too each of the NSToolbarItems options, and then draw the corresponding view on to the custom view when the specified NSToolbarItem is clicked.
I'm guessing that I simply create a NSView sub-class for each view, an empty xib in Interface Builder - set the xib to my custom NSView, code it as usual... But here's a few problems;
1 - Just how can I get the xib file to appear on the custom-view then? I have looked around and most articles don't seem to have this situation, or a situation I can relate too.
2 - When the window comes up, I want the default view to appear on the custom view. Once again, I'm guessing I just write that in the initialisation code for the NSWindow - its no big deal. It just goes back to question 1 though - how do I draw my NSView to the custom-view specified in Interface Builder?
I'd be really grateful for any help!
Cheers in advance.
So I set the NSToolbar and its items in Interface Builder, and then placed a custom view underneath the menu - taking up the rest of the window.
You can't have a menu inside of a window. You can have a pop-up button, which has a menu, but not a menu directly. Did you mean “toolbar” here?
You don't need to create a custom view for this. Make a tab view and set it to be tabless. Give it as many tab view items as you have toolbar items. In your controller, write an action method for each of the toolbar items, and in each action method, switch the active tab of the tab view.
You can activate different tabs in IB to populate them with views in IB. The active tab is saved in the nib, so make sure you set it back to the first tab before saving, so that the first tab is the one that's initially active when your app runs.
Just how can I get the xib file to appear on the custom-view then?
That question doesn't make sense.
Once again, I'm guessing I just write that in the initialisation code for the NSWindow - its no big deal.
You would only be able to do that if you have your own initialization code for the window, which you would only have if you have subclassed NSWindow. There are very few reasons to do that; unless you're making the window itself look different (not making an Aqua or HUD window), you should move that initialization code elsewhere, probably to the aforementioned controller (which should be the File's Owner of the nib).
It just goes back to question 1 though - how do I draw my NSView to the custom-view specified in Interface Builder?
A custom view in Interface Builder is a plain NSView (unless you explicitly change it to a subclass of NSView you create). However, you do not need one for anything you have described in your question.